I got myself a bucket of water, and didn't hold it any time between getting it and losing it. I did a few things, like check my furnace and chest, and when I looked back at my hotbar, my water was randomly gone (I still had the bucket, the bucket just randomly became empty). I looked everywhere I went, and there was no trace of water. I already knew I didn't accidentally put the water back in the river I got it from, since I was looking at it for about 5-10 seconds, until I got into my home. I tried acting like there was water in the bucket, by right-clciking the ground, but nothing happened. When I got some more water, it only took me one right-click, instead of two if there was already water in the bucket. It appears my water had vanished.